作曲家不自动加载

I followed the composer instructions and installed composer successfully. I want to use tumblr's brand new php api client.

我的文件夹结构:

vendor/
composer.json
composer.lock
myfile.php

composer.json:

{
    "require": {
        "tumblr/tumblr": "0.0.2"
    }
}

myfile.php:

require 'vendor/autoload.php';
$client = new TumblrAPIClient(CONSUMER_KEY, CONSUMER_SECRET);

使用 php composer.phar install 安装也很有效.但是在执行 myfile.php 时找不到该类.